Mechanical keyboards are popular input mechanisms for many processing devices. But in the realm of small electronic devices such as cell phones and personal digital assistants (PDAs), the size of mechanical keyboards is a serious limitation. To accommodate small electronic devices, past attempts at providing a mechanical keyboard have included shrinking the keyboard size and making the keyboard an attachable accessory.
More recently, digital keyboards have been employed for use with PDAs and similar devices. A digital keyboard is an image of a keyboard displayed on a contact-sensitive screen. Such keyboards are typically operable by a user that directs a stylus into contact with the contact-sensitive screen. The user selects keys from the keyboard by using the stylus to contact the keyboard in areas where specific keys of the keyboard are displayed.
One problem encountered with digital keyboards is that the users typically miss the center of the key that they wish to select. Often, the area that is contacted is a region shared by two keys. Because digital keyboards offer no tactile feedback for key selection, the user is often unaware that the area being contacted on the contact-sensitive area is in between keys. Furthermore, digital keyboards offer no tactile resistance, so that even if the user could tell that they selected an area in between keys, the user cannot physically force the actuation of one key over another key. Thus, the key that the user actually selects may not be the key that the user intended to select.
One approach that has been presented in dealing with the problem of ambiguous key selection for digital keyboards is to use a language-based algorithm to determine which key a user intended to select. A language-based algorithm looks at a sequence of selected keys and determines if one of the keys was mistakenly entered. If a mistake is detected, a correction may be made that replaces the key determined as being a mistake. For example, the language-based model may replace successive entries of the digital keyboard corresponding to “tge” with “the”.
Light-generated keyboards are recent innovations. Such keyboards project the image of a keyboard onto a table top or other surface. As with digital keyboards, light-generated keyboards typically provide no tactile feedback or resistance to the user. Thus, the user has little ability to detect when a key selection was ambiguous or otherwise off-center. Should the user select an area in between keys, the user cannot physically manipulate the selection of one key over another, as is the case with traditional mechanical keyboards.
In the drawings, the same reference numbers identify identical or substantially similar elements or acts. To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the Figure number in which that element is first introduced. Any modifications necessary to the Figures can be readily made by one skilled in the relevant art based on the detailed description provided herein.